content: /*
   * Copyright 2011-2016 David Karnok
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package ix;
  
  import java.util.Iterator;
  
  final class IxTransformer<T, R> extends IxSource<T, R> {
  
      final IxTransform<T, R> transform;
  
      IxTransformer(Iterable<T> source, IxTransform<T, R> transform) {
          super(source);
          this.transform = transform;
      }
  
      @Override
      public Iterator<R> iterator() {
          return new TransformerIterator<T, R>(source.iterator(), transform);
      }
  
      static final class TransformerIterator<T, R> extends IxSourceIterator<T, R>
      implements IxConsumer<R> {
  
          final IxTransform<T, R> transform;
  
          TransformerIterator(Iterator<T> it, IxTransform<T, R> transform) {
              super(it);
              this.transform = transform;
          }
  
          @Override
          protected boolean moveNext() {
              int m = transform.moveNext(it, this);
              if (m == IxTransform.LAST) {
                  done = true;
                  return true;
              }
              if (m == IxTransform.STOP) {
                  value = null;
                  done = true;
                  return false;
              }
              if (!hasValue) {
                  throw new IllegalStateException("No value set!");
              }
              return true;
          }
  
          @Override
          public void accept(R t) {
              if (hasValue) {
                  throw new IllegalStateException("Value already set in this turn!");
              }
              value = t;
              hasValue = true;
          }
      }
  }
  